It is generally known that during CT examinations scattered radiation effects are produced that lead to inaccuracies in the measurement of the absorption of X-radiation. Looking first at this effect in unifocal detector systems, the problem of scattered radiation here becomes larger the wider the beam fan used is expanded, since the sites at which scattered radiation is produced increase correspondingly. In the case of such CT systems, these known effects are counteracted by fitting in front of the detector so called scattered radiation collimators that expose in front of each detector element only the direct radiation direction between detector element and focus, and largely shade all the other directions. Such scattered radiation collimators are also used with the bifocal or multifocal detector systems. However, these scattered radiation collimators cannot diminish the scattered radiation that are produced by beams of another focus arranged with an angular offset and whose alignment has the same spatial orientation as the actual direct beam that originates from a focus opposite the detector and whose intensity is to be measured.
There is, furthermore, a complication that the examined objects—which are preferably different patients in this case—vary in their spatial configuration from examination to examination, and so, when the aim is to examine with adequate safety, the scattered radiation generated can only be determined individually. Moreover, the examined object is to be subjected during an examination only to the lowest possible dose, and so numerous test scans that could be used only to determine the scattered radiation should be avoided.